call this below method from oncreate of your activity , it will print a hash key in logcat, add that into hash field in app setting on Facebook. try again it will work
public void printHashKey() {
try {
PackageInfo info = getPackageManager().getPackageInfo("your.package.name",
PackageManager.GET_SIGNATURES);
for (Signature signature : info.signatures) {
MessageDigest md = MessageDigest.getInstance("SHA");
md.update(signature.toByteArray());
Log.d("TEMPTAGHASH KEY:",
Base64.encodeToString(md.digest(), Base64.DEFAULT));
}
} catch (NameNotFoundException e) {
} catch (NoSuchAlgorithmException e) {
}
}